Characters random die.
I don't knwo why, or how?
But I am sure I am not using any special mod that makes characters randomly die.

This sounds like the "map seam bug". Try moving your characters away from the standard landing areas, where the maps join is known to cause random gibbing for no reason.

It happens if you have too many of them at a time. or does it happens no matter how many you have ?

@ MrC121989: The seam bug happens even if there are just a few actors wobbling around.

I expect the queen of england will sooner be replaced by a labotomized monkey (actually a good idea, no one would know the difference) before data actually fixes this at least 9-build (=4 years) long old bug.

Yeah i wanted to edit it in my post, but then i noticed Roast Veg posted this before me, so i dropped the idea.

I am having this issue as well. Characters that are nowhere near battle seemingly die at random intervals for no reason. My miners occasionally die. Snipers in sentry mode occasionally die. I am found this forum and searched for a fix or answer after my brain died a few times down in the bunker, ending my battle. The game is very cool, but this is stopping me from enjoying it, any idea?